(1) Field of the Invention
The present invention relates to in-line skates and, more particularly, to an independent suspension system thereof that uses an elastomer in the form of a synthetic resin spring, a non-limiting example of which is a polyurethane spring.
(2) Description of Related Art
In-line skates are well known, and have essentially replaced regular roller-skates, and are used by speed skaters and ice-hockey players for dry-land activities. In general, in-line skates are used outside on sidewalks and other road surfaces that may be uneven, which can cause stress on the wheels, boots, and other structural elements of the skate as well as discomfort for the skater.
In the past, systems and mechanisms have been developed to improve the suspension system of the in-line skate so that the skate will absorb the shocks caused on the skate by uneven riding surfaces. Reference is made to the following few exemplary U.S. Patent Publications, including U.S. Pat. Nos. 7,048,281; 6,644,673; and 6,454,280, all to Longino, the entire disclosures of all of which patents is expressly incorporated by reference in their entirety herein.
As illustrated in FIG. 1A, prior art conventional suspension systems use a polyurethane spring 100 that has a smooth and even outer surface, and that is captured within a smooth and even cavity 106 of rocker arms 102 and 104, which are compressed into the polyurethane spring 100. As best illustrated in FIGS. 1B to 1G, the prior art polyurethane spring 100 generally includes a through-hole 108, which provides a more flexible spring compared with solid polyurethane springs that are more rigid. As seen in FIGS. 1B to 1D, the through-hole 108 can be of any general shape wherein each shape provides for different degrees of variability for the spring 100. In addition to the regular elasticity of the polyurethane, the through-hole 108 provides space into which polyurethane material can additionally move. The size and dimension of the through-hole 108 can effect the rigidity of the spring 100, and as can be appreciated, the larger the surface area of the through-hole 108, the more variability that is provided by the spring 100.
In prior art springs 100, in order to further adjust their strength or resistance, an adjustment post 110 (FIG. 1E) is placed into the through-hole 108. The post 110 placed within the through-hole 108 reduces the size (volume) of the void space of the through-hole, and hence, reducing the space into which polyurethane material can additionally move and thereby, increasing spring 100 resistance. The size of the adjustment post 110 from the furthest edges formed by the wave-like shape is proximate the size of the through-hole 108 so that the post 110 fits easily into the through-hole 108 while engaging the spring 100 at the sides of the through-hole 108. The adjustment rod 110 is made of a suitably rigid material so that it can contribute to the variability of the spring 100. The adjustment rod 110 must also be flexible so that when the spring 100 flexes within the confines of the hole 108 the integrity of the rod is maintained and that it will return to its original shape when the force is removed from the spring. FIGS. 1F and 1G illustrate the spring 100 with the adjustment post 110 in two different positions thereby changing and varying the rigidity of the spring 100. In FIG. 1F, the post 110 is in the vertical position whereby the spring material is given the greatest area to flex within the hole 108 (least resistance); in FIG. 1G, the post 110 is in the horizontal position whereby the spring material does not have the same ability to deform, or flex within the hole and provides a more rigid spring than that compared to FIG. 1F. In addition, the adjustment rod 110 itself contributes to the rigidity of the spring 100. The adjustment post 110 can be rotated between the vertexes of the hole 108 to vary the strength or resistance of the spring. As the post 110 rotates from a vertical orientation to a horizontal orientation, the strength of the spring is enhanced. As the post is moved to the horizontal, the resistance within the space is increased against the pressing of the rocker arms, thereby making a more rigid spring.
As described above, regrettably, the prior art suspension systems are complicated, and require user meddling with the suspension system for adjustment of the spring resistance for specific users. Further, having the holes within springs also means that the springs would not function properly with heavier weight individuals, and hence, the need for the post. Therefore, the prior art suspension systems must be particularized and specifically made and adjusted for different individuals, which makes the use and manufacturing of the entire in-line skates too complicated and costly, with variations in the quality of the end product.
In addition, the prior art suspension systems have a limited range of resistance for different user weights, and have an undesired responsiveness in terms of their rate of resistance in relation to shifting of user weight during the ride of the in-line skates (for example, during quick, sharp turns when large amounts of force are applied to the spring). Further, the prior art suspension systems that use the adjustment rod are prone to breakage. In particular, when the adjustment rod is turned horizontally, it can only contact two of the vertexes of the holes while the rest of the vertices remain free. This creates uneven resistances within the spring hole, which can easily cause cracking and breakage of the spring due to fatigue under very large forces on only two vertexes.
Accordingly, in light of the current state of the art and the drawbacks to current polyurethane springs mentioned above, a need exists for a spring apparatus that would provide a wide range of resistance to accommodate a smooth ride against the application of different forces and, more particularly, that would provide a rate of resistance that would commensurately vary and be correspondingly responsive in relation to shifting of user weights during the ride of the in-line skates, without requiring any adjustments. In addition, a need exists for such an apparatus that would be simple and not require user meddling with the suspension system for adjustment of resistance and rate of resistance of the spring.